Electrochemical Behavior of Scandium in LiF–CaF₂–ScF₃ Melt

Abstract—The electrochemical behavior of scandium in halide melts is of interest from the viewpoint of developing new electrochemical approaches to produce scandium and related materials. In addition, scandium is used to simulate the electrochemical behavior of fission products at nuclear waste pyrochemical reprocessing in molten layers. The electrolytic reduction of scandium ions versus the parameters of LiF–CaF₂–ScF₃ melt electrolysis has been studied by means of cyclic voltammetry, square wave voltammetry, and chronopotentiometry at 800°C. It has been shown that electrochemical reduction of scandium in the given melt takes place at a potential more negative than –0.45 V relative to the potential of the aluminum electrode. In this case, the scandium reduction on the electrode favors the reduction of lithium cations with depolarization. The analysis of polarization dependences has shown that the scandium reduction has one three-electrode stage and is not electrochemically reversible. It has been supposed that irreversibility is the result of new phase formation. The conclusion has been drawn that owing to a wide electrochemical window, LiF–CaF₂ melt may be used for electrochemical synthesis of scandium and analysis of joint or selective electrochemical reduction of many actinides and lanthanides.